matita/matita/contribs/lambdadelta/delayed_updating/reduction/dfr.ma

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  14
  15 include "delayed_updating/syntax/path_structure.ma".
  16 include "delayed_updating/syntax/path_balanced.ma".
  17 include "delayed_updating/substitution/fsubst.ma".
  18 include "delayed_updating/notation/relations/black_rightarrow_4.ma".
  19
  20 (* DELAYED FOCALIZED REDUCTION **********************************************)
  21
  22 inductive dfr (p) (q) (t): predicate preterm ≝
  23 | dfr_beta (b) (n):
  24   let r ≝ p●𝗔◗b●𝗟◗q◖𝗱❨n❩ in
  25   r ϵ t → ⊓⊗b → dfr p q t (t[⋔r←t⋔(p◖𝗦)])
  26 .
  27
  28 interpretation
  29   "delayed focalized reduction (preterm)"
  30   'BlackRightArrow t1 p q t2 = (dfr p q t1 t2).